diff --git a/src/rebar_port_compiler.erl b/src/rebar_port_compiler.erl
index a347cb7..2f419c9 100644
--- a/src/rebar_port_compiler.erl
+++ b/src/rebar_port_compiler.erl
@@ -253,7 +253,9 @@ default_env() ->
                                      " -I", filename:join(erts_dir(), include),
                                      " "])},
      {"DRIVER_LDFLAGS", lists:concat([" -L", code:lib_dir(erl_interface, lib),
-                                      " -lerl_interface -lei"])}].
+                                      " -lerl_interface -lei"])},
+     {"ERLANG_ARCH", 8 * erlang:system_info(wordsize)},
+     {"ERLANG_TARGET", erlang:system_info(system_architecture)}].